Process of fabricating babbitt lined bearings



Sept. 11, 1945.

S. A. SMITH PROCESS OF FABRICATING BABBIT'I' LINED BEARINGS Filed July 15, 1942 FIG].

Flea.

INVENTOR.

SALEM A SMITH ATTORNEYS Patented Sept. ll, 1945 PROCESS OF FABRICATING BABBITT LINED BEARINGS Salem A. Smith, Greenviile, Mich., asslgnor to Federal-Mogul Corporation, Detroit, Mich., a

corporation of Michigan Application July 13, 1942, Serial No. 450,733 3 Claims. (Cl. 29-1495) This invention relates to a method of fabricating steel back bearings having copper base alloy linings, particularly such as are made by applying lining material initially in the form of minutely pulverized metal constituents, a quite wide diversity of the exact components used being very generally spoken of as Babbitt" llnings.

Numerous alloys for hearing liner purposes are now in use, for example, with proportioned contributents of copper and lead, sometimes with small added percentages of one or more of such components as tin, nickel, silver, sulphur and tellurium.

Various methods of applying these alloys are also known and have been resorted to with varying degrees of success; for example, one method contemplates the pouring of a heated alloy into a heated shell within a suitable mould and thereafter rapidly chilling the same, thereby fusing or bonding the alloy to the shell. Another method involves the spinning of the melted alloy in the heated shell followed by rapid chilling.

Metal powders of various constituent proportionings have also been used as the base material for such bearing liners. In some cases these have been of copper and lead admixtures only; in others, fine particles of lead coated with copper have been employed. Still another kind has been composed of grindings or finely divided particles of the copper base metal previously alloyed to the desired composition by fusion. In some instances tin has been used in small percentages in association with these other components. The addition of a small quantity of graphite as still another element is also known. And sometimes a chemical is added to the metal powder for the purpose of producing porosity in the bearing liner, for the absorption of lubricating oil.

The bonding of metal powders of one composition or another to a steel bearing back has resulted in the evolvement of various methods, one being the compression of powder upon the bearing face of a steel back which has been electroplated or otherwise coated with a thin layer of copper, followed by the sintering of the powder layer into position at a relatively high temperature, thereby bonding the particles of powder together and bonding the layer as a whole to the copper-plated steel back.

Various kinds of metal powder have been used thus, one, for example, a mixture of copper and lead powders in varying proportions; another is composed of fine particles of lead coated with copper. Still another kind is composed of grinding's or finely divided particles of the copper base metal previously alloyed to the composition by fusion. Tin, also graphite, particles are other components often resorted to in association with the copper and lead and sometimes a chemical is added to the metal powders for the purpose oi producing porosity. which latter is supposed to cause the absorption of lubricating oil.

One method for forming the liner from metal powder involves the use of an expanding core of rubber or other iormable and elastic substance. The necessary degree of pressure in this case is relatively high because the pressure upon the liner material must be such that it will stay in position during handling before it is sintered.

It has been my experience that none of the processes hereinabove illustratively mentioned are wholly satisfactory from a manufacturing or endurance standpoint. It has been found that impurities became integrated in the metal steel back A with when the melted alloy was poured into a steel bearing shell, thus reducing to an objectionable degree the bearing properties of the finished bearing; and not only is an objectionably high temperature required when the melted alloy is poured into the steel bearing shell, but as well all too extensive subsequent machining operations were required for the removal of excess alloy. Machining operations are always required to remove excess metal thus deposited, but in this case the excess is very great. By my method such excess is reduced to a minimum.

An additional objection to previously known practices is found in the fact that it the pressures used be high, blistering of the applied bearing' layer will take place, and that if pressure be applied during sintering to prevent blistering, lead sweating will occur. This may not always be the case where a bearing layer is applied to fiat steel banks or strips, but is all too prevalent an objection in the fabrication of full round lined bearings.

My improved process, while contemplating the full range of above enumerated constituents or selections therefrom to make a suitable alloy, avoids theobjections in the manufacturing steps heretofore noted, as well as in the completed article. As before, I first electroplate or equivalently coat the bearing surface of the full round tin, copper, or other suitable bonding metal or a compound of two or more. or them. I cups over the ends 01 the steel backing, one cup E being preferably provided with a vent hole then apply steel ends E or shallow.

in the center through which gases from the reducing agent, such as salicylic acid, may escape.

This preferred form of association of the temporarily positioned cups or ends with the bearing under treatment is illustrated in the drawing,

Figure 1 being a sectional side elevational view showing the same as mounted in a spinning mechanism or centrifugal casting machine, and

Figure 2 being a partly sectional and partly elevational end view thereof.

With one of the end cups in place on the bearing shell A, the required quantity of metal powder is introduced through the open end, there being preferably mixed with it a small quantity of salicylic acid or equivalent reducing agent. The vented end cup E is then pressed into position on the other end of the bearing shell and the terminal closing shells are then clamped between the rotating plates F of a suitable spinning or centrifugal casting machine. The bearing shell is then rotated and contemporaneously therewith vibration is applied on the outside to assist in the even spreading of the powder, the speed of rotation being gradually increased until the powder clings to the inner surface of the shell. The rate of rotation necessary will of course depend upon the diameter of the shell, but it may be illustratively stated that for a bearing quarter inches in diameter a rotative speed of two hundred revolutions per minute has been found satisfactory.

During the rotation of the shell heat is applied to the outside of the shell by some such means as a gas burner as G, until the inner surface of the shell reaches a temperature between 1000 and 1200 Fahrenheit, in other words, until the steel shell has attained a dull-red heat. At this temperature the metal powder will partially sinter into a spongy layer and will adhere to the surface of the steel bearing shell A. This temperature is maintained for selectively varying periods, and following the termination of its application the rotation of the shell is continued to effect its gradual cooling back to substantial room temperature.

The shell is then taken from the rotating machine and the end caps removed. It is then placed in a furnace and heated in a reducing atmosphere at a temperature of preferably about 1200 Fahrenheit, though, dependent upon the circumstances of individual cases a temperature range of from ll00 to 1700 Fahrenheit is possible. This treatment further bonds the powder particles together and the layer as a whole to the shell. The shell is then cooled in a reducing atmosphere and the metal liner is then compressed by rolling or equivalent treatment equivalent to a pressure of from 2500 lbs. to 20,000 lbs. per square inch, depending upon the composition and the thickness of the metal powder layer. Final sintering then follows in a reducing temperature at a temperature of about 1700 Fahrenheit, to further bond the powder layer to the steel back as well as to thoroughly unite the particles of powder. Cooling is effected as before in a reducing atmosphere. The lining B in the finally sintered condition may then be rolled to the desired hardness, or it may be machined to finished size without rolling.

Dependent of course on the specifications for the particular bearing being worked upon, one of the above-described sintering operations above described may, in some instances, be omitted, and

shell two-and-a- I desire the scope of this disclosure to be understood accordingly.

As brought out particularly in Figure 2 of the drawings, it has been my experience that it is sometimes desirable to trowel or pare the applied layer B to very uniform thickness during the spinning or rotating operation by inserting a spiral shaped tool D through the vent hole E in one of the caps, as C. An equivalently functioning paring tool could, if desired, be applied in a position to act perpendicularly to the direction of its active edge as here shown, that is to say, said edge lying in parallel relation to the longitudinal axis of the bearing shell A. The small amount of powder thus removed is collected and held in the center portion D of the spiral tool.

It will of course be obvious that while the described process steps are directed particularly to full round bearings of either plain or flanged type, half bearings may be fabricated therefrom by sawing the full round hearings in half along a truly diametrical line.

It will further be obvious that the omission of the use of dies in following the process herein described is of great advantage whether the full round bearing being treated is of either the plain or flanged type A, and furthermore that the metal powder as applied is not subjected to severe pressure to hold it in position, and that it will not crack or shrink laterally, or form blisters in subsequent sintering operations; and further that the avoidance of the necessity of using high pressure is of great advantage in that avoidance of leading, sweating and blistering is made possible.

What I claim is:

1. The method of lining a bearing shell with a coating of selected bearing material, which consists in first positioning therewlthin a predetermined quantity of non compacted pulverized bearing-forming material and then positioning temporary end-closure members over the ends of said shell, then rotating said shell to effect the spinning of its included pulverized material over the interior surface of the shell and the diffused adherence to one another of the constituent particles of the introduced bearing-forming material, while contemporaneously subjecting the shell to heating action until a constituent metal has attained a dull-red degree of heat though distinctly below the melting point of the introduced pulverized material; then terminating the heating action while continuing the shell's rotative movement in a reducing atmosphere until said shells temperature has returned to its initial normal degree, then removing the temporary end closure pieces and again subjecting the shell and its then adherent lining to further sintering action in a reducing atmosphere within a tem-' perature range of 1100" to l700 Fahrenheit rolling the then adherent bearing lining to desired hardness, again subjecting the shell to sintering action in a reducing atmosphere, and thereafter subjecting the interior bearing surface thereof to a machine-effected finishing operation.

2. The method of applying a diffusely applied layer of initially pulverized bearing metal to the interior surface of a bearing shell, which consists in positioning within the latter a selected quantity of such pulverized material, positioning temporary closure members over the ends thereof, then contemporaneously spinning and vibrating the shell to effect initial distribution of its deposited pulverized contents over its interior surface contemporaneously with the raising of the temperature thereof to a point distinctly below the melting point of the contained metal powder, thereafter terminating the heating thereof while continuing the spinning action, then removing the end closure plates and subjecting the shell and its then difiusedly adherent bearing layer to sintering action under a temperature range of l100 to 1700 Fahrenheit, and then, after allowing the shell to return to normal temperature, mechanically effecting the finishing of the surface of the bearing layer.

3. The method of lining a bearing shell with an adherent coating of initially pulverized bearing material, which consists in first positioning therewithin a non-compacted mass of such selected material, positioning temporary end-closure members over the ends of the shell, then rotating the shell to eflect the spinning of its included pulverized material over the interior surface of the shell and its diffused mass adherence thereto while contemporaneously subjecting the exterior of the shell to heating influence of appreciably lower degree than the melting point of the introduced pulverized bearing material, then terminating the heating treatment while continuing the shells rotative movement, then removing the end-closure members and again sub jecting the shell and its then adherent lining to sintering action contemporaneously with the subjection thereof to further heating of a degree between 1100 and 1700 Fahrenheit, and thereafter subjecting the surface of the diffusedly applied bearing surface to finishing mechan- SALEM A. SMITH,

. ical treatment. 

